Art of cracking hydrocarbons.



J. W. COA'SY, 1n.

AHUF CRACKING HYDRCARBONS.

Patented Mar. 5,1918.

APPLIICATION FILED MAR. 22. 19|?. 1,258,190.

Umtrnn STATES PATENT` onirica. I

JOHN W. COAST, JR., OF TU LSA, OKLAHOMA, ASSIGNOIR T0 THE PROCESSCOMPANY, A

CORPORATION OF MARYLAND.

ABT OF CRACKING HYDROGARBONS.

To-all 'who-m t may concern.' Y

Be it known that I, JOHN W. CoAs'r, Jr., a citizen of the United vStatesof America, a resident of Tulsa, in the county of Tulsa, State ofOklahoma, have invented certain new and useful Improvements in the Artof Cracking Hydrocarbons, of which the following is afull, clear, andexact description, reference being had to the accompanying drawing,forming a part of this specification;

My invention relates to improvements in the art of crackinghydrocarbons, and more particularly to a method of protecting stillsfrom the'injurious effects of coke ortarry coke-forming substances.

When high boiling point petroleum hydrocarbons are vaporized and crackedin the ordinary cylindrical still, heavy cokeforming substances settleto the bottom of the liquid in the still. If the coke or carbon ispermitted to collect on'the still bottom, it will prevent the freetransmission of heat to the liquid contents of the still, and when asufficient quantity has accumulated, the still bottom will become redhot. lSome u a rupture at the overheated portion of the still. In actualpractice', the coke accumulates on the hot still bottom when the oil inthel still is maintained at a high temperature and under a highpressure, thus rendermg the cracking operation quite dangerous. Onaccount ofthe danger, and foreconomic reasons the coke is usuallyremoved from the still at frequent intervals.

The main object of my. inventionfis to prevent the coke, or tarrycoke-forming. substances from accumulating on the stillbottom where theheat is transmitted tothe still. In the preferred form of the invention,this is accomplished -by maintaining a body of heavy liquid in thebottom of the still, floating the oil to be distilled on said heavyliquid and transmitting heat through the heavyg'liquid to vaporize the.oating liquid. The heavy liquid, preferably molten metal, interposedbetween the still bottom and the oil, prevents the cokeforming substancefrom v reaching the bottom Vof the still. Since theheat cannot betransmitted readily through the coke or carbon, the latter ,ispreferably circulated or skimmed along the surface of the heavy liquidto the end portions of the By preventingY Specification of 'LettersPatent. Application ledlMarch 22, 1917. Serial No. 156,649.

Patented Mar. 5, 1918.

be overheated by the temperature to which it is ordinarily subjected.

Figure I is a diagrammatical view of a cracking apparatus embodying thelfeatures of my invention.

Fig. II is a transverse section ofthe still taken on the line II--II,Fig. I.

Fig. III is a detail view of the filler vwhereby the heavy liquid isdisplaced to area of the still botcontact with a greater tom.

The still 1, arranged above a heating l chamber 2, is connected by meansof an air cooled vapor pipe' 3 toa reflux condenser 4. 5 designates avapor pipe leading from the reflux condenser to a main condensing coil 6from which the low boiling point product is recovered. The condensingcoil 6 is preferably arranged in a water tank 7. The

air cooled vapor pipe 3 constitutes a reiux condenser, and it isinclined to allow the condensate to How backwardly to the still.

The apparatusrI have shown is particularly adapted for use in crackinghigh boiling point products of distillation such, for example, as thedistillates or residues resulting from the distillation of the crudepetroleum. The substances to be treated are introduced into the still inany suitable manner, and any desired pressure may be obtained byregulating a valve 8, preferably located in the vapor pipe 5. Thepressure in the still is preferably greater than fifty' pounds persquare4 inch, and the temperature of the contents of the stillpreferably ranges from about 600 F. to 800 F. The

low boiling point vapors passing from the liquid, flow through thevvapor pipe 3 and v reux condenser 4 to the pipe 5, leading tothe maincondenser 6. The relativelyjhigh boiling point fractions are condensedin the vapor pipe 3 or in the condenser 4, such fractions being returnedto the still through the inclined vapor pipe 3. 'This reflux condensateincludes al large percentage of heavy coke-formn fractions, commingledwith lighter fractlons, which may be redistilled to form part vof thelow boiln point product.

In the preferred form o the invention, the 'end portions of the bottomare ber, an thsefwalls protect said end porseated u on the walls 9 ofthe heating chamtio'nsi'from the intense heat of thev heating chamber.The heat is transmitted directly through lthe middle portion of thestill bottom, and the protected end portions of the stillxare maintained`in a relatively cool condition. l v

A body of heavy liquid."10,=preferably a' readily fusible metal, forexample, molten lead,.is ymaintained'in the bottom :of thestillf- The'oil to-be distilled iioats upon the surface-c ofthe molten lead'10,and'the Aheavy coke#- forming fractions whichl dro V.by gravity to thebottom of the'oiL, also oat upon the lead. The molten' lead thuspreventsthe coke-forming substance from reaching the hot still bottom.The heat' is transmittedl from' the still bottom, through the molten'lead to the floating oil. Owingto the high temperature, the lead. iscirculated and ay i5 tated so as to very effectively transmlt t eheat tothe oil.'4

. The coke is not a .ood conductor of heat;

and fitiis, therefore, circulated along the sur? face of the lead topoints directly above the Walls 9, Where it will not materiallyinterfere with the transmission of heat fromtlie4r heating chamber tothe oil.

The means forl circulating o r skimming" the coke comprises a skimmer 11tted t'o a.l rotary feed screw 12 which extends through a stuiing` box13 atone end of the still..

Gearing -12 may beoperatedin any suitable manner to rotate the. feedscrew 12.' Thisl 'feed screw is reversible, so that it ma vbe actuatedto reciprocate the skimmer 11 romV one endl portion of the still to theother. Stationary rods 14 prevent the skimmer 11' from turning on thefeed scre1vv12.v The lower portion of the `skimmer extends entirelyacross the lower portion of the still,-

and it' also'extends into the molten lead 10.

By confining the oil and inolten lead, as herein shown and-described, Ipreventthe vapors', generated in the' still, fromipassing into, orbubblingthrough the moltenliea'd.

The` vapors are discharged from the upper portion of thel still -at avpoi'ntlabovethe ilji 15 designates a filling device, in the form of .a.coil of quantity Aof lead. This filling device 15 displaces some of theDlead, causing 1t to protect a greater areaof the still.- The c oil ofpipe constituting the filling device is capped i e, submerged in themolten lead to .avoi t e use'of an' extremely 'large' the device 15 fromflating'on Vth's'urface o the molten lead." Q

I claim--' v 1. In the artv of crackingwand distilling hydrocarbons, themethod which comprises maintaininga body of heavy liquid on the bottomof a still, floating the liquid to be cracked and distilled on saidheavyliquid,

transmitting heat through said heavy liquid.

to vaporizc the oating liquid, collecting coke-forming substance on thesurface of the heavyliquid at the bottom of said float- 1n 'I liquid,circulating such coke-forming" su stance between the heavyliquid and theoatin liquid 'to facilitate the transmission-o heat from said heavyliquid to said voating"liquid, maintainin the contents of thestill underressure, and 'vapors from t e still at a point above the floatingliquid.

` 2.' The method of'distilling and cracking' hydrocarbons -whichcomprises -maintaining a body of heavy liquid on the bottom of a still'floating. the liquid to be distilled and crac ed yon said heavy liquid,4transmitting heatI through` the still bottom and through dischargingthe *saidf heavy liquid to vaporize the floating liquid, dischargingthevapors. from the still -at a plae above the floating .liquid withoutconducting said vaporsv into said heavy hquid, collecting' coke-formingsubstance on the! surface ofthe heavy liquid, and v.forcing suchcoke-forming substancealong the surV of the still.

I -testimon that vI claim? the foregoing h eeuntoa mv signature.

' JOHN COAST, JR.'

*face of said heavy liquid tothe end portions

